1. Cell Phone

1. Cell Phone

This gadget is like the Swiss Army knife of undercover sex toys. Put it on vibrate, and it'll give you and your guy's hot spots a body-quivering buzz. Or use the video function to record a naughty flick—even though you'll (wisely) hit delete as soon as the deed is over, just knowing you're being filmed is a ridiculous turn-on. And if you've got an iPhone, use Cosmo's Sex Position of the Day app for naughty inspiration.